Radiation image conversion panels equipped with radiation conversion layers constituted by a plurality of columnar crystals (acicular crystals) have conventionally been known. A radiation image conversion panel of this kind is constructed by providing a phosphor layer in which crystals of a phosphor are grown like columns on a base constituted by amorphous carbon, for example. Since the base such as amorphous carbon has such a low reflectance as to make it hard to enhance the light utilization efficiency by itself, radiation image conversion panels formed with reflective layers made of thin films of metals such as aluminum have conventionally been known (see Patent Literatures 1 and 2). On the other hand, there has been known a radiation image conversion panel in which, on a side face of columnar crystals, the width of their undulation is made to fall within a predetermined range, so as to enhance the linearity of the columnar crystals, thereby improving the quality of radiation images (see, for example, Patent Literature 3). Further, a radiation image conversion panel having enhanced its reflectance without forming reflective layers has been known (see, for example, Patent Literature 4).